1. Field of the Invention
The present invention relates to a liquid ejection head for ejecting liquid droplets from an ejection port so as to perform printing on a print medium and, more particularly, to a liquid ejection head provided with a plurality of kinds of ejection ports having different opening areas, and a fabricating method therefor.
2. Description of the Related Art
In a printing apparatus in which liquid such as ink is ejected from a fine ejection port formed in a liquid ejection head so as to perform printing, the evaporation of liquid (e.g., ink) to be ejected from a nozzle may cause a viscosity increasing phenomenon of the liquid, an increase in concentration of a colorant contained in the liquid, adhesion of the liquid, and the like. Moreover, if the apparatus is left for a long period of time, bubbles may be generated inside of a liquid channel of the liquid ejection head. The generation of the bubbles prevents a normal ink supplying operation. Depending on the situation, the ink may not flow in the head, thereby hindering a printing operation.
In order to avoid the above-described inconvenience, a surface of the liquid ejection head having an ejection port formed thereat (i.e., an ejection port surface) is capped with a cap, and further, a pump reduces pressure inside of the cap, so that a suction recovery process for sucking liquid from the ejection port is performed. In the suction recovery process, ink that stays inside of the liquid channel and becomes unsuitable for printing or bubbles are forcibly sucked from the ejection port: in the meantime, the liquid channel is filled with fresh liquid from a liquid tank. In this manner, the suction recovery process is properly carried out, so that the ink staying in the liquid ejection head can be kept suitable for ejection.
However, in a liquid ejection head having ejection ports having different opening areas arranged at the same ejection port surface so as to achieve high printing precision and high-speed printing, ejection ports having different meniscus forces exist in mixture, thereby making it difficult to properly perform the suction recovery process. Specifically, when a suction negative pressure is increased in order to suck and recover a small ejection port, a flow rate of liquid from a large ejection port exceeds the liquid supply ability of a liquid tank, and consequently, bubbles are taken into the ink channel from an absorber of the liquid tank, resulting in insufficient ink supply. In order to cope with this inconvenience, Japanese Patent Laid-Open No. 2005-059554 discloses a suction recovery process, in which a large ejection port is first sucked under a low suction negative pressure to be thus filled with ink, before a high suction negative pressure is instantaneously applied, so that a small ejection port is filled with liquid.